The Cancer Microbiome: Recent Highlights and Knowledge Gaps

Autophagy: The convergence point of aging and cancer

Autophagy, a dynamic intracellular degradation system, is critical for cellular renovation and maintaining equilibrium. By eliminating damaged components and recycling essential molecules, autophagy safeguards cellular integrity and function. The versatility of the autophagy process across various biological functions enable cells to adapt and maintain homeostasis under unfavourable conditions. Disruptions in autophagy can shift a cell from a healthy state to a disease state or, conversely, support a return to health. This review delves into the multifaceted role of autophagy during aging and age-related diseases such as cancer, highlighting its significance as a unifying target with promising therapeutic implications. Cancer development is a dynamic process characterized by the acquisition of diverse survival capabilities for proliferating at different stages. This progression unfolds over time, with cancer cells exploiting autophagy to overcome encountered stress conditions during tumor development. Notably, there are several common pathways that utilize the autophagy process during aging and cancer development. This highlights the importance of autophagy as a crucial therapeutic target, holding the potential to not only impede the growth of tumor but also enhance the patient's longevity. This review aims to simplify the intricate relationship between cancer and aging, with a particular focus on the role of autophagy.

Ellagic acid-protein nano-complex inhibits tumor growth by reducing the intratumor bacteria and inhibiting histamine production

In recent years, there has been growing interest in understanding the role of bacteria within tumors and their potential as targets for cancer therapy. In this work, we developed an ellagic acid (EA) - endogenous protein (eP) nanocomposite (eP-EA) to target tumors by EPR (enhanced permeability and retention), kill bacteria within tumors to regulate anti-tumor immune responses. The potential mechanism of eP-EA treatment is associated with the reduced abundance and diversity of microorganisms within the tumor, culminating with an altered metabolism within the Tumor microenvironment (TME). Among them, the metabolite histamine that contributes to tumor progression, is significantly reduced in the TME after eP-EA treatment. We show that one possible mechanism by which these microbes promote tumor growth is through the production of histamine. This work suggests that the ellagic acid (EA)-protein nano complex can enhance cancer immunotherapy by targeting the intratumoral bacteria and reduce their production of histamine, delineating the potential relationship between intratumor bacteria and their impact on tumors. Our work suggests that the EA-protein nano complex can enhance cancer immunotherapy by targeting the intratumoral bacteria, suggesting the role of bacterial metabolites in contributing to tumor progression.

Advances in research on the intestinal microbiota in the mechanism and prevention of colorectal cancer (Review)

The intestinal microbiota represents a diverse population that serves a key role in colorectal cancer (CRC) and its treatment outcomes. Advancements in sequencing have revealed notable shifts in microbial composition and diversity among individuals with CRC. Concurrently, animal models have elucidated the involvement of specific microbes such as Lactobacillus fragilis, Escherichia coli and Fusobacterium nucleatum in the progression of CRC. The present review aimed to highlight contributions of intestinal microbiota to the pathogenesis of CRC, the effects of traditional treatments on intestinal microbiota and the potential for microbiota modulation as a therapeutic strategy for CRC.

A Nano-Strategy for Advanced Triple-Negative Breast Cancer Therapy by Regulating Intratumoral Microbiota

Intratumoral microbiota have been identified as a component of the tumor microenvironment that regulates the metastatic behavior of tumors. They serve not only as indicators of tumor pathology but also as potential drug targets in cancer therapy. Herein, a multifunctional nanoplatform (DD@FEL) is prepared by combining antibiotic doxycycline (DOXY) that can combat intratumoral microbiota and the chemotherapeutic drug doxorubicin (DOX) in ergosterol-originated liposome. Specially, ergosterol is utilized as a substitute for cholesterol in liposomes to exert pharmacological activity. Mechanistically, DD@FEL leveraged DOXY to inhibit cancer metastasis based on the regulation of intratumoral microbiota, which synergizes with the chemotherapeutic effect of DOX, eventually inhibiting the progression of triple-negative breast cancer (TNBC). Verified both in vitro and in vivo, DD@FEL effectively exerts a cytotoxic effect on TNBC cells, delays the growth of primary TNBC, and attenuates the development of its lung metastasis, providing a promising therapeutic strategy to control both orthotopic and metastatic TNBC.

The influence of Lactobacillus johnsonii on tumor growth and lymph node metastasis in papillary thyroid carcinoma

Lymph node metastasis (LNM) is a key factor in the prognosis of papillary thyroid carcinoma (PTC). This study explores the effect of intratumoral bacteria on LNM in PTC. The intrathyroidal microbiome is analyzed in 55 PTC patients by 16S rRNA gene sequencing. The CCK8 and Transwell assays determine the impact of bacteria on the proliferation and migration abilities of PTC cells. Xenograft tumor and bacterial colonization experiments are carried out using nude mice. We show that Lactobacillus is significantly decreased in PTC lesions from patients with LNM. Lactobacillus johnsonii (L. johnsonii) suppresses the proliferation and migration capability of PTC cells in vitro and in vivo. Bacterial gut colonization of L. johnsonii increases its abundance in tumors and inhibits PTC growth and LNM. These findings suggest that L. johnsonii can be harnessed for the development of innovative therapeutic strategies for PTC.

Gut microbiota as a new target for anticancer therapy: from mechanism to means of regulation

In order to decipher the relationship between gut microbiota imbalance and cancer, this paper reviewed the role of intestinal microbiota in anticancer therapy and related mechanisms, discussed the current research status of gut microbiota as a biomarker of cancer, and finally summarized the reasonable means of regulating gut microbiota to assist cancer therapy. Overall, our study reveals that the gut microbiota can serve as a potential target for improving cancer management.

Associations of the gut, cervical, and vaginal microbiota with cervical cancer: a systematic review and meta-analysis

BACKGROUND

An increasing number of studies indicate that the gut, cervical, and vaginal microbiota may play crucial roles in the development of cervical cancer (CC). However, the interactions between the microbiota and the host are yet unknown. To address this gap, a systematic review and meta-analysis were conducted to assess the microbiota alterations in a variety of body locations, including the gut and genital tract.

METHODS

Electronic searches of PubMed, Embase, Web of Science, and the Cochrane Library were conducted to retrieve eligible papers published from January 1, 2014, to January 1, 2024 (PROSPERO: CRD42024554433). This study was restricted to English-language studies reporting on alpha diversity, beta diversity, and relative abundance, as well as on patients with CC whose microbiota had been analyzed via next-generation sequencing technologies. To assess the risk of bias (RoB), we utilized the Newcastle‒Ottawa Quality Assessment Scale (NOS) and the ROBINS-I tool. For the meta-analysis, we employed Review Manager 5.4.

RESULTS

Thirty-six eligible studies were included in this review. The Chao1 index (SMD = 0.96, [95% CI: 0.71, 1.21], I2 = 0%) and the Shannon index (SMD = 1.02, [95% CI: 0.53, 1.50], I2 = 85%) values from vaginal samples were significantly greater in patients than in the controls. In the cervical samples, the Shannon index value (SMD = 1.29, [95% CI: 0.61, 1.97], I2 = 93%) significantly increased, whereas the Chao1 index value did not significantly differ (SMD = 0.50, [95% CI: -0.46, 1.46], I2 = 89%). The Shannon index value (SMD = 0.25, [95% CI: -0.22, 0.72], I2 = 38%) did not significantly differ across the gut samples. The majority of studies (19/25) indicated that the patients and noncancer controls differed significantly in terms of beta diversity. Cancer-associated changes were observed, with a dramatic decrease in the Lactobacillus genus and significant increases in pathogenic bacteria, including the Anaerococcus, Peptostreptococcus, Porphyromonas, Prevotella, and Sneathia genera. Additionally, the impact of antineoplastic therapies on microbial diversity was inconsistently reported across several studies.

CONCLUSION

This systematic review elucidates the microbiota alterations associated with the prevalence of CC and its response to anti-tumor therapies, aiming to provide insights for future research directions and precision medicine strategies to enhance women's quality of life.

PROSPERO REGISTRATION

CRD42024554433.

Microbiome Integrity Enhances the Efficacy and Safety of Anticancer Drug

The intricate relationship between anticancer drugs and the gut microbiome influences cancer treatment outcomes. This review paper focuses on the role of microbiome integrity in enhancing the efficacy and safety of anticancer drug therapy, emphasizing the pharmacokinetic interactions between anticancer drugs and the gut microbiota. It explores how disruptions to microbiome composition, or dysbiosis, can alter drug metabolism, immune responses, and treatment side effects. By examining the mechanisms of microbiome disruption caused by anticancer drugs, this paper highlights specific case studies of drugs like cyclophosphamide, 5-fluorouracil, and irinotecan, and their impact on microbial diversity and clinical outcomes. The review also discusses microbiome-targeted strategies, including prebiotics, probiotics, postbiotics, and fecal microbiota transplantation (FMT), as promising interventions to enhance cancer treatment. Furthermore, the potential of microbiome profiling in personalizing therapy and integrating these interventions into clinical practice is explored. Finally, this paper proposes future research directions, including developing novel biomarkers and a deeper comprehension of drug-microbiome interactions, to respond to current gaps in knowledge and improve patient outcomes in cancer care.

Low transthyretin is associated with the poor prognosis of colorectal cancer

Objective

To determine whether transthyretin (TTR) influences the prognosis of patients with colorectal cancers and establish a predictive model based on TTR.

Methods

Between January 2013 and February 2019, the clinical data of 1322 CRC patients aged from 18 years to 80 years who underwent surgical treatment were retrospectively analyzed. The preoperative TTR level, clinicopathological data, and follow-up data were recorded. The X-tile program was used to determine the optimal cut-off value. Cox proportional hazard regression analysis was conducted to evaluate the correlation between the TTR and the cumulative incidence of cancer-specific survival (CSS). Nomograms were then developed to predict CSS. Furthermore, an additional cohort of 377 CRC patients enrolled between January 2014 and December 2015 was included as an external validation.

Results

Based on the optimal cut-off value of 121.3 mg/L, we divided the patients into the TTR-lower group (<121.3 mg/L) and the TTR-higher group (≥121.3 mg/L). Comparative analysis revealed that the TTR-higher group exhibited a younger demographic, a higher prevalence of low colorectal cancers, an elevated R0 resection rate, superior differentiation, earlier stage and lower levels of carcinoembryonic antigen (CEA) in contrast to the TTR-lower group. The Cox multivariable analysis underscored the significance of TTR and various clinicopathological factors, encompassing age, tumor location, R0 resection status, differentiation grade, disease stage, postoperative chemoradiotherapy, and preoperative CEA levels, as substantial prognostic indicators. The postoperative survival nomogram, when internally and externally assessed, demonstrated commendable performance across multiple metrics, including the area under the receiver operating characteristic curve (AUC), calibration plots, and decision curve analysis (DCA). Compared with other models, the proportional hazards model combined with TTR demonstrates superior performance in terms of C-index, AUC, calibration chart, and DCA within the prognostic column chart.

Conclusions

The preoperative TTR was identified as a prognostic factor for predicting the long-term prognosis of CRC patients who underwent surgical treatment, supporting its role as a prognostic biomarker in clinical practice.

Dencichine attenuates the virulence of Fusobacterium nucleatum by targeting hydrogen sulfide-producing enzyme

Oral opportunistic pathogen Fusobacterium nucleatum can participate in various disease processes through the metabolite hydrogen sulfide, such as halitosis and colorectal cancer. The object of this study is to identify inhibitor capable of suppressing Fn1220, which is the principal hydrogen sulfide-producing enzyme in F. nucleatum. Through this inhibition, we aim to reduce the hydrogen sulfide production of F. nucleatum, consequently diminishing its virulence. Employing molecular docking techniques for inhibitor screening, we identified dencichine as the monomeric compound from Chinese medicine exhibiting the lowest binding energy to Fn1220 among a set of 27,045 candidates, and evaluated in vitro the ability of dencichine to inhibit hydrogen sulfide production using bismuth chloride method. Additionally, we investigated its impact on key virulence factors, including biofilm formation, hemolysis, and adhesion factors of F. nucleatum, using the crystalline violet method, sheep blood method, and RT-qPCR, respectively. Furthermore, we assessed the influence of dencichine on the lifespan of Caenorhabditis elegans. Results showed that dencichine was a suitable inhibitor of the Fn1220 of F. nucleatum, which significantly inhibited the production of virulence factors, e.g., biofilm, hemolysin, FadA, and Fap2 of F. nucleatum and improved the survival of C. elegans. We successfully identified the inhibitor of the enzyme Fn1220, dencichine, which inhibited the production of hydrogen sulfide and attenuated the virulence of F. nucleatum and holds promise as a potential therapeutic avenue for addressing oral diseases, e.g., halitosis in the future.

Integrative multi-omics analysis uncovers tumor-immune-gut axis influencing immunotherapy outcomes in ovarian cancer

Recurrent ovarian cancer patients, especially those resistant to platinum, lack effective curative treatments. To address this, we conducted a phase 2 clinical trial (NCT02853318) combining pembrolizumab with bevacizumab, to increase T cell infiltration into the tumor, and oral cyclophosphamide, to reduce the number of regulatory T cells. The trial accrued 40 heavily pretreated recurrent ovarian cancer patients. The primary endpoint, progression free survival, was extended to a median of 10.2 months. The secondary endpoints demonstrated an objective response rate of 47.5%, and disease control in 30% of patients for over a year while maintaining a good quality of life. We performed comprehensive molecular, immune, microbiome, and metabolic profiling on samples of trial patients. Here, we show increased T and B cell clusters and distinct microbial patterns with amino acid and lipid metabolism are linked to exceptional clinical responses. This study suggests the immune milieu and host-microbiome can be leveraged to improve antitumor response in future immunotherapy trials.

The oral-gut microbiome axis in health and disease

The human body hosts trillions of microorganisms throughout many diverse habitats with different physico-chemical characteristics. Among them, the oral cavity and the gut harbour some of the most dense and diverse microbial communities. Although these two sites are physiologically distinct, they are directly connected and can influence each other in several ways. For example, oral microorganisms can reach and colonize the gastrointestinal tract, particularly in the context of gut dysbiosis. However, the mechanisms of colonization and the role that the oral microbiome plays in causing or exacerbating diseases in other organs have not yet been fully elucidated. Here, we describe recent advances in our understanding of how the oral and intestinal microbiota interplay in relation to their impact on human health and disease.

Existence and distribution of the microbiome in tumour tissues of children with hepatoblastoma

Cancer microbiota have recently been demonstrated in several cancer types. The microbiome enhances inflammation in the cancer microenvironment and affects the disease pathology by regulating tumourigenesis, cancer progression, and chemotherapy resistance. Hepatoblastoma (HB), the most common childhood malignant tumour, is a malignant embryonic tumour. However, the pathogenesis and molecular basis of HB remain poorly understood. In this study, to explore the existence and distribution of the microbiome in tumour tissues and adjacent non-tumour tissues of children with HB, we mainly performed 16S rDNA sequencing, and the results showed that the diversity and abundance of the microbiome in children with HB were significantly different between HB tumours and adjacent non-tumour tissues (p < 0.01). At the phylum level, the dominant microbiome in the tumour tissues were Proteobacteria, Bacteroidetes, and Firmicutes. At the genus level, Ruminococcus was more abundant in HB tumours than in the adjacent non-tumour tissues. Simultaneously, the abundances of Bacteroides, Parabacteroides, Lachnospiracea-NK4A136, and Alistipes in HB tumours were lower than those in the adjacent non-tumour tissues. In addition, Romboutsia strongly correlated with alpha-fetoprotein, an important indicator of HB. Sphingomonas was abundant in primary HB tumours, whereas Oscillibacter and Pandoraea were abundant in metastatic HB tumours. However, whether these bacteria are associated with HB needs further evaluation. Therefore, we identified the microbiome that correlated with the occurrence and development of HB. Ruminococcus and Romboutsia were identified as potential bacterial markers of HB tumours. To conclude, we found that HB also contains cancer microbiome, and it is necessary to shed light on the microbiome characteristics of HB in the future.

The role of short-chain fatty acids in cancer prevention and cancer treatment

Short-chain fatty acids (SCFAs) are microbial metabolites in the gut that may play a role in cancer prevention and treatment. They affect the metabolism of both normal and cancer cells, regulating various cellular energetic processes. SCFAs also inhibit histone deacetylases, which are targets for cancer therapy. The three main SCFAs are acetate, propionate, and butyrate, which are transported into cells through specific transporters. SCFAs may enhance the efficacy of chemotherapeutic agents and modulate immune cell metabolism, potentially reprogramming the tumor microenvironment. Although SCFAs and SCFA-generating microbes enhance therapeutic efficacy of several forms of cancer therapy, published data also support the opposing viewpoint that SCFAs mitigate the efficacy of some cancer therapies. Therefore, the relationship between SCFAs and cancer is more complex, and this review discusses some of these aspects. Clearly, further research is needed to understand the role of SCFAs, their mechanisms, and applications in cancer prevention and treatment.

Reduction of butyrate-producing bacteria in the gut microbiome of Japanese patients with pancreatic cancer

BACKGROUND

The incidence of pancreatic cancer is on the rise, and its prognosis remains poor. Recent reports have established a link between the gut and oral microbiome and pancreatic cancer. However, the intricacies of this association within the Japanese population remain unclear. In this study, we investigated the gut and oral microbiomes of Japanese patients with pancreatic cancer, comparing them with those of healthy individuals.

METHODS

We recruited 30 patients with untreated pancreatic cancer and 18 healthy controls at Kyoto University Hospital (2018-2022). We performed a comprehensive 16S rRNA gene sequencing to analyze their gut and oral microbiomes.

RESULTS

Analysis revealed that the diversity of the gut and oral microbiomes of patients with pancreatic cancer was reduced compared to that of the healthy controls. Specifically, we observed an increase in the genus Streptococcus in both the gut and oral microbiomes and a significant decrease in several butyrate-producing bacteria in fecal samples. Moreover, bacteria such as Streptococcus mitis and Holdemanella biformis were present in pancreatic cancer tissues, suggesting that they might influence the carcinogenesis and progression of pancreatic cancer.

CONCLUSIONS

The gut and oral microbiome differed between patients with pancreatic cancer and healthy controls, with a notable decrease in butyrate-producing bacteria in the gut microbiome of the patients. This suggests that there may be a distinct microbial signature associated with pancreatic cancer in the Japanese population. Further studies are required to elucidate the microbiome's causal role in this cancer and help develop prognostic markers or targeted therapies.

Effect analysis of 847 nasopharyngeal carcinoma cases treated with intensity modulated radiation: Experience and suggestions

OBJECTIVES

To identify the failure patterns and prognostic factors of nonmetastatic nasopharyngeal carcinoma (NPC) in the intensity-modulated radiotherapy (IMRT) era.

METHODS

Data on 847 patients with newly diagnosed, non-disseminated NPC treated by IMRT between 2012 and 2016 were retrospectively reviewed. Survival outcome, failure patterns and prognosis factors were analyzed.

RESULTS

The 5-year local relapse-free survival, nodal relapse-free survival, distant metastasis-free survival, disease-free survival, and overall survival rates were 94.3%, 95.3%, 84.8%, 76.5% and 85.7%, respectively. The major local recurrence sites were the nasopharynx (91.5%, 43/47) and skull base (68.1%, 32/47); 39 patients had in-field failures, four had marginal failures, and four had out-field failures. Level IIb (62.2%, 23/37) was the most frequent regional recurrence site, followed by IIa (35.1%, 13/37) and retropharyngeal region (32.4%, 12/37); 35 cases had in-field failure alone, one had out-field failure alone, and one had both in- and out-field failure. TNM stage was the most significant factor for prognosis prediction. 402 (47.5%) patients had acute adverse events of grade 3 or 4; leukopenia (31.5%) and mucositis (26.7%) was the most common hematological and non-hematological event, respectively. Late complications were slight or moderate damages; xerostomia (647/847, 76.4%) and hearing impairment (422/847, 49.8%) remained the most troublesome.

CONCLUSION

NPC patients treated with IMRT obtained satisfactory survival outcomes. The key failure pattern was distant metastasis. The main pattern of local-regional failure was in-field failure. Screening high risk patients with distant metastases and optimizing radiotherapy targets should be studied.

Tumor-colonized Streptococcus mutans metabolically reprograms tumor microenvironment and promotes oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) remains a major death cause in head and neck cancers, but the exact pathogenesis mechanisms of OSCC are largely unclear.

RESULTS

Saliva derived from OSCC patients but not healthy controls (HCs) significantly promotes OSCC development and progression in rat models, and metabolomic analyses reveal saliva of OSCC patients but not HCs and OSCC tissues but not adjacent non-tumor tissues contain higher levels of kynurenic acid (KYNA). Furthermore, large amounts of Streptococcus mutans (S. mutans) colonize in OSCC tumor tissues, and such intratumoral S. mutans mediates KYNA overproductions via utilizing its protein antigen c (PAc). KYNA shifts the cellular types in the tumor microenvironment (TME) of OSCC and predominantly expedites the expansions of S100a8highS100a9high neutrophils to produce more interleukin 1β (IL-1β), which further expands neutrophils and induces CD8 + T cell exhaustion in TME and therefore promotes OSCC. Also, KYNA compromises the therapeutic effects of programmed cell death ligand 1 (PD-L1) and IL-1β blockades in oral carcinogenesis model. Moreover, KYNA-mediated immunosuppressive program and aryl hydrocarbon receptor (AHR) expression correlate with impaired anti-tumor immunity and poorer survival of OSCC patients.

CONCLUSIONS

Thus, aberration of oral microbiota and intratumoral colonization of specific oral bacterium such as S. mutans may increase the production of onco-metabolites, exacerbate the oral mucosal carcinogenesis, reprogram a highly immunosuppressive TME, and promote OSCC, highlighting the potential of interfering with oral microbiota and microbial metabolism for OSCC preventions and therapeutics. Video Abstract.

Beyond the Gut: The intratumoral microbiome's influence on tumorigenesis and treatment response

The intratumoral microbiome (TM) refers to the microorganisms in the tumor tissues, including bacteria, fungi, viruses, and so on, and is distinct from the gut microbiome and circulating microbiota. TM is strongly associated with tumorigenesis, progression, metastasis, and response to therapy. This paper highlights the current status of TM. Tract sources, adjacent normal tissue, circulatory system, and concomitant tumor co-metastasis are the main origin of TM. The advanced techniques in TM analysis are comprehensively summarized. Besides, TM is involved in tumor progression through several mechanisms, including DNA damage, activation of oncogenic signaling pathways (phosphoinositide 3-kinase [PI3K], signal transducer and activator of transcription [STAT], WNT/β-catenin, and extracellular regulated protein kinases [ERK]), influence of cytokines and induce inflammatory responses, and interaction with the tumor microenvironment (anti-tumor immunity, pro-tumor immunity, and microbial-derived metabolites). Moreover, promising directions of TM in tumor therapy include immunotherapy, chemotherapy, radiotherapy, the application of probiotics/prebiotics/synbiotics, fecal microbiome transplantation, engineered microbiota, phage therapy, and oncolytic virus therapy. The inherent challenges of clinical application are also summarized. This review provides a comprehensive landscape for analyzing TM, especially the TM-related mechanisms and TM-based treatment in cancer.

Intratumoral microbiota as a novel prognostic indicator in bladder cancer

Microbes are important components of the tumor microenvironment and have a close relationship with tumors. However, there is still a lack of research on the intratumoral microbiota in bladder cancer and its impact on the tumor immune microenvironment. In this study, we used fluorescence in situ hybridization (FISH) and observed a substantial presence of microbiota in bladder cancer tissues, with greater abundance compared to that in normal bladder tissues. Based on the BIC database, we found that the microbiome of bladder cancer is highly diverse and its structure is significantly different from that of other tumors. To investigate the relationships among the intratumoral microbiota, tumor immunity, and prognosis in bladder cancer patients, we analyzed bladder cancer-specific differentially expressed immune- and antimicrobial-related genes from the ImmPort, TISIDB, and TCGA databases. We identified 11 hub genes and constructed a prognostic risk model. Further analysis revealed differences at the family and genus levels between distinct groups. Using LEfSe analysis, we identified six hub biomarkers and developed a novel microbial-based scoring system. The scoring system allows subgrouping of bladder cancer patients, with significant differences in prognosis, immune cell infiltration, tumor mutation burden, and immune checkpoints among different groups. Further FISH and immunofluorescence co-staining experiments initially verified that the specific distribution of microorganisms and M2 macrophages in bladder cancer may be closely related to the poor prognosis of patients. In conclusion, this study revealed the characteristics of the intratumoral microbiota in bladder cancer and identified potential prognostic targets for clinical application.

Disruption of the intestinal clock drives dysbiosis and impaired barrier function in colorectal cancer

Diet is a robust entrainment cue that regulates diurnal rhythms of the gut microbiome. We and others have shown that disruption of the circadian clock drives the progression of colorectal cancer (CRC). While certain bacterial species have been suggested to play driver roles in CRC, it is unknown whether the intestinal clock impinges on the microbiome to accelerate CRC pathogenesis. To address this, genetic disruption of the circadian clock, in an Apc-driven mouse model of CRC, was used to define the impact on the gut microbiome. When clock disruption is combined with CRC, metagenomic sequencing identified dysregulation of many bacterial genera including Bacteroides, Helicobacter, and Megasphaera. We identify functional changes to microbial pathways including dysregulated nucleic acid, amino acid, and carbohydrate metabolism, as well as disruption of intestinal barrier function. Our findings suggest that clock disruption impinges on microbiota composition and intestinal permeability that may contribute to CRC pathogenesis.

Intratumoral microbiota of pancreatic ductal adenocarcinoma impact patient prognosis by influencing tumor microenvironment

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a highly metastatic potential and a heterogeneous tumor microenvironment. It exhibits limited sensitivity to conventional therapies, necessitating a deeper understanding of its pathogenesis. The role of the intratumoral microbiome in regulating cancer development in PDAC has been the subject of debate. Previous investigations into intra-tumor microbiomes have yielded uncertain results due to sample size limitations and insufficient decontamination procedures. Further research is imperative to elucidate the intricate relationship between intra-tumor microbiomes, the immune landscape of PDAC, and overall prognosis.

RESULTS

Our findings revealed that the intratumor microbiota in PDAC tissue exhibited lower diversity and distinct communities compared to non-tumor tissues. The top microorganisms distinguishing between patients with long or short survival were used to construct the risk signature. We found that Stenotrophomonas is implicated in short survival of PDAC patients, while Neorickettia and Mediterraneibacter are correlated with long survival. This microbiome-based PDAC subtyping, grounded in prognosis-related signatures, exhibited significant correlations with distinct clinical prognoses and immune microenvironments. Microorganisms associated with negative prognoses were linked to pro-tumor immune activation, while those associated with positive prognoses were linked to anti-tumor immune response activation and a more favorable prognosis.

CONCLUSIONS

Our PDAC subtyping approach, based on a microbiome-derived prognostic risk signature, unveiled compelling associations between the PDAC microbiota and disparities in both clinical prognosis and the tumor microenvironment. These findings suggest that microbiota may serve as a promising biomarker for predicting the prognosis of PDAC.

Oncogene-addicted solid tumors and microbiome-lung cancer as a main character: a narrative review

Background and Objective

Lung cancer stands as the main cause of cancer-related deaths worldwide. With the advent of immunotherapy and the discovery of targetable oncogenic driver genes, although prognosis has changed in the last few years, survival rates remain dismal for most patients. This emphasizes the urgent need for new strategies that could enhance treatment in precision medicine. The role of the microbiota in carcinogenesis constitutes an evolving landscape of which little is known. It has been suggested these microorganisms may influence in responses, resistance, and adverse effects to cancer treatments, particularly to immune checkpoint blockers. However, evidence on the impact of microbiota composition in oncogene-addicted tumors is lacking. This review aims to provide an overview of the relationship between microbiota, daily habits, the immune system, and oncogene-addicted tumors, focusing on lung cancer.

Methods

A PubMed and Google Scholar search from 2013 to 2024 was conducted. Relevant articles were reviewed in order to guide our research and generate hypothesis of clinical applicability.

Key Content and Findings

Microbiota is recognized to participate in immune reprogramming, fostering inflammatory, immunosuppressive, or anti-tumor responses. Therefore, identifying the microbiota that impact response to treatment and modulating its composition by interventions such as dietary modifications, probiotics or antibiotics, could potentially yield better outcomes for cancer patients. Additionally, targeted therapies that modulate molecular signaling pathways may impact both immunity and microbiota. Understanding this intricate interplay could unveil new therapeutic strategies.

Conclusions

By comprehending how microbiota may influence efficacy of targeted therapies, even though current evidence is scarce, we may generate interesting hypotheses that could improve clinical practice.

Gut microbial metabolites in lung cancer development and immunotherapy: Novel insights into gut-lung axis

Metabolic derivatives of numerous microorganisms inhabiting the human gut can participate in regulating physiological activities and immune status of the lungs through the gut-lung axis. The current well-established microbial metabolites include short-chain fatty acids (SCFAs), tryptophan and its derivatives, polyamines (PAs), secondary bile acids (SBAs), etc. As the study continues to deepen, the critical function of microbial metabolites in the occurrence and treatment of lung cancer has gradually been revealed. Microbial derivates can enter the circulation system to modulate the immune microenvironment of lung cancer. Mechanistically, oncometabolites damage host DNA and promote the occurrence of lung cancer, while tumor-suppresive metabolites directly affect the immune system to combat the malignant properties of cancer cells and even show considerable application potential in improving the efficacy of lung cancer immunotherapy. Considering the crosstalk along the gut-lung axis, in-depth exploration of microbial metabolites in patients' feces or serum will provide novel guidance for lung cancer diagnosis and treatment selection strategies. In addition, targeted therapeutics on microbial metabolites are expected to overcome the bottleneck of lung cancer immunotherapy and alleviate adverse reactions, including fecal microbiota transplantation, microecological preparations, metabolite synthesis and drugs targeting metabolic pathways. In summary, this review provides novel insights and explanations on the intricate interplay between gut microbial metabolites and lung cancer development, and immunotherapy through the lens of the gut-lung axis, which further confirms the possible translational potential of the microbiome metabolome in lung cancer treatment.

Harnessing microbial antigens as cancer antigens: a promising avenue for cancer immunotherapy

Immunotherapy has revolutionized cancer treatment by leveraging the immune system's innate capabilities to combat malignancies. Despite the promise of tumor antigens in stimulating anti-tumor immune responses, their clinical utility is hampered by limitations in eliciting robust and durable immune reactions, exacerbated by tumor heterogeneity and immune evasion mechanisms. Recent insights into the immunogenic properties of host homologous microbial antigens have sparked interest in their potential for augmenting anti-tumor immunity while minimizing off-target effects. This review explores the therapeutic potential of microbial antigen peptides in tumor immunotherapy, beginning with an overview of tumor antigens and their challenges in clinical translation. We further explore the intricate relationship between microorganisms and tumor development, elucidating the concept of molecular mimicry and its implications for immune recognition of tumor-associated antigens. Finally, we discuss methodologies for identifying and characterizing microbial antigen peptides, highlighting their immunogenicity and prospects for therapeutic application.

The intratumoral microbiota: a new horizon in cancer immunology

Over the past decade, advancements in high-throughput sequencing technologies have led to a qualitative leap in our understanding of the role of the microbiota in human diseases, particularly in oncology. Despite the low biomass of the intratumoral microbiota, it remains a crucial component of the tumor immune microenvironment, displaying significant heterogeneity across different tumor tissues and individual patients. Although immunotherapy has emerged a major strategy for treating tumors, patient responses to these treatments vary widely. Increasing evidence suggests that interactions between the intratumoral microbiota and the immune system can modulate host tumor immune responses, thereby influencing the effectiveness of immunotherapy. Therefore, it is critical to gain a deep understanding of how the intratumoral microbiota shapes and regulates the tumor immune microenvironment. Here, we summarize the latest advancements on the role of the intratumoral microbiota in cancer immunity, exploring the potential mechanisms through which immune functions are influenced by intratumoral microbiota within and outside the gut barrier. We also discuss the impact of the intratumoral microbiota on the response to cancer immunotherapy and its clinical applications, highlighting future research directions and challenges in this field. We anticipate that the valuable insights into the interactions between cancer immunity and the intratumoral microbiota provided in this review will foster the development of microbiota-based tumor therapies.

Tumor initiation and early tumorigenesis: molecular mechanisms and interventional targets

Tumorigenesis is a multistep process, with oncogenic mutations in a normal cell conferring clonal advantage as the initial event. However, despite pervasive somatic mutations and clonal expansion in normal tissues, their transformation into cancer remains a rare event, indicating the presence of additional driver events for progression to an irreversible, highly heterogeneous, and invasive lesion. Recently, researchers are emphasizing the mechanisms of environmental tumor risk factors and epigenetic alterations that are profoundly influencing early clonal expansion and malignant evolution, independently of inducing mutations. Additionally, clonal evolution in tumorigenesis reflects a multifaceted interplay between cell-intrinsic identities and various cell-extrinsic factors that exert selective pressures to either restrain uncontrolled proliferation or allow specific clones to progress into tumors. However, the mechanisms by which driver events induce both intrinsic cellular competency and remodel environmental stress to facilitate malignant transformation are not fully understood. In this review, we summarize the genetic, epigenetic, and external driver events, and their effects on the co-evolution of the transformed cells and their ecosystem during tumor initiation and early malignant evolution. A deeper understanding of the earliest molecular events holds promise for translational applications, predicting individuals at high-risk of tumor and developing strategies to intercept malignant transformation.

Recent progress in nanomaterials for bacteria-related tumor therapy

Many studies suggest that tumor microbiome closely relates to the oncogenesis and anti-tumor responses in multiple cancer types (e.g., colorectal cancer (CRC), breast cancer, lung cancer and pancreatic cancer), thereby raising an emerging research area of bacteria-related tumor therapy. Nanomaterials have long been used for both cancer and bacterial infection treatment, holding great potential for bacteria-related tumor therapy. In this review, we summarized recent progress in nanomaterials for bacteria-related tumor therapy. We focus on the types and mechanisms of pathogenic bacteria in the development and promotion of cancers and emphasize how nanomaterials work. We also briefly discuss the design principles and challenges of nanomaterials for bacteria-related tumor therapy. We hope this review can provide some insights into this emerging and rapidly growing research area.

The microbial landscape of colorectal cancer

Colorectal cancer (CRC) is a substantial source of global morbidity and mortality in dire need of improved prevention and treatment strategies. As our understanding of CRC grows, it is becoming increasingly evident that the gut microbiota, consisting of trillions of microorganisms in direct interface with the colon, plays a substantial role in CRC development and progression. Understanding the roles that individual microorganisms and complex microbial communities play in CRC pathogenesis, along with their attendant mechanisms, will help yield novel preventive and therapeutic interventions for CRC. In this Review, we discuss recent evidence concerning global perturbations of the gut microbiota in CRC, associations of specific microorganisms with CRC, the underlying mechanisms by which microorganisms potentially drive CRC development and the roles of complex microbial communities in CRC pathogenesis. While our understanding of the relationship between the microbiota and CRC has improved in recent years, our findings highlight substantial gaps in current research that need to be filled before this knowledge can be used to the benefit of patients.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

Revealing the role of the gut microbiota in enhancing targeted therapy efficacy for lung adenocarcinoma

Lung adenocarcinoma (LUAD) is the leading cause of cancer-related death globally. Although the gut microbiota's role in the antitumor efficacy of many cancers has been revealed, its involvement in the response to gefitinib therapy for LUAD remains unclear. To fill this gap, we conducted a longitudinal study that profiled gut microbiota changes in PC-9 tumor-bearing mice under different treatments, including gefitinib monotherapy and combination therapies with probiotics, antibiotics, or Traditional Chinese Medicine (TCM). Our findings demonstrated that combining probiotics or TCM with gefitinib therapy outperformed gefitinib monotherapy, as evidenced by tumor volume, body weight, and tumor marker tests. By contrast, antibiotic intervention suppressed the antitumor efficacy of gefitinib. Notably, the temporal changes in gut microbiota were strongly correlated with the different treatments, prompting us to investigate whether there is a causal relationship between gut microbiota and the antitumor efficacy of gefitinib using Mediation Analysis (MA). Finally, our research revealed that thirteen mediators (Amplicon Sequence Variants, ASVs) regulate the antitumor effect of gefitinib, regardless of treatment. Our study provides robust evidence supporting the gut microbiota's significant and potentially causal role in mediating gefitinib treatment efficacy in mice. Our findings shed light on a novel strategy for antitumor drug development by targeting the gut microbiota.

Current advances in bacteria-based cancer immunotherapy

As the understanding of the tumor microenvironment has deepened, immunotherapy has become a promising strategy for cancer treatment. In contrast to traditional therapies, immunotherapy is more precise and induces fewer adverse effects. In this field, some bacteria have attracted increased attention because of their natural ability to preferentially colonize and proliferate inside tumor sites and exert antitumor effects. Moreover, bacterial components may activate innate and adaptive immunity to resist tumor progression. However, the application of bacteria-based cancer immunotherapy is hampered by potential infection-associated toxicity and unpredictable behavior in vivo. Owing to modern developments in genetic engineering, bacteria can be modified to weaken their toxicity and enhance their ability to eliminate tumor cells or activate the antitumor immune response. This review summarizes the roles of bacteria in the tumor microenvironment, current strategies for bacterial engineering, and the synergistic efficiency of bacteria with other immunotherapies. In addition, the prospects and challenges of the clinical translation of engineered bacteria are summarized.

Advances and challenges of first-line immunotherapy for non-small cell lung cancer: A review

The current use of immune checkpoint inhibitors (ICIs) for the treatment of lung cancer has dramatically changed the clinical strategy for metastatic non-small cell lung cancer (mNSCLC). As a result of great achievements in clinical trials, 6 programmed death-1 inhibitors (sintilimab, camrelizumab, tislelizumab, pembrolizumab, cemiplimab, and nivolumab), 2 programmed death-ligand 1 inhibitors (sugemalimab and atezolizumab), and 1 cytotoxic T lymphocyte-associated antigen-4 inhibitor (ipilimumab) have been approved as first-line treatment for mNSCLC by the US Food and Drug Administration. Recently, research on ICIs has shifted from a large number of second-line to first-line settings in clinical trials. Results from first-line trials have shown that almost all driver-negative mNSCLC are treated with ICIs and significantly prolong patient survival; however, the low response rate and adverse reactions to immunotherapy remain to be addressed. Here, we summarize the use of ICIs, including monotherapy and combination therapy, in the first-line treatment of mNSCLC in recent years and discuss the low response rate and adverse reactions of ICIs as well as the challenges and expectations for the first-line treatment of mNSCLC in the future.

Urinary microbiota signatures associated with different types of urinary diversion: a comparative study

Background

Radical cystectomy and urinary diversion (UD) are gold standards for non-metastatic muscle-invasive bladder cancer. Orthotopic neobladder (or Studer), ileal conduit (or Bricker) and cutaneous ureterostomy (CU) are mainstream UD types. Little is known about urinary microbiological changes after UD.

Methods

In this study, urine samples were collected from healthy volunteers and patients with bladder cancer who had received aforementioned UD procedures. Microbiomes of samples were analyzed using 16S ribosomal RNA gene sequencing, and microbial diversities, distributions and functions were investigated and compared across groups.

Results

Highest urine microbial richness and diversity were observed in healthy controls, followed by Studer patients, especially those without hydronephrosis or residual urine, α-diversity indices of whom were remarkably higher than those of Bricker and CU groups. Studer UD type was the only independent factor favoring urine microbial diversity. The urine microflora structure of the Studer group was most similar to that of the healthy individuals while that of the CU group was least similar. Studer patients and healthy volunteers shared many similar urine microbial functions, while Bricker and CU groups exhibited opposite characteristics.

Conclusion

Our study first presented urinary microbial landscapes of UD patients and demonstrated the microbiological advantage of orthotopic neobladder. Microbiota might be a potential tool for optimization of UD management.

Dietary medium-chain fatty acids and risk of incident colorectal cancer in a predominantly low-income population: a report from the Southern Community Cohort Study

BACKGROUND

No prospective observational study has specifically examined the associations between dietary intakes of medium-chain fatty acids and risk of colorectal cancer.

OBJECTIVES

This study examined the association between dietary intakes of medium-chain fatty acids and colorectal cancer risk overall and by racial subgroups in a predominantly low-income United States population.

METHODS

This prospective study included 71,599 eligible participants aged 40 to 79 who were enrolled in the Southern Community Cohort Study between 2002 and 2009 in 12 southeastern United States states. Incident colorectal cancer cases were ascertained via linkage to state cancer registries, which was completed through 31 December, 2016. The dietary intakes of medium-chain fatty acids were assessed using a validated 89-item food frequency questionnaire. Multivariable Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations between intakes of medium-chain fatty acids and risk for incident colorectal cancer.

RESULTS

Among 71,599 participants, 48,008 (67.3%) were Black individuals and 42,260 (59.0%) were female. A total of 868 incident colorectal cancer cases occurred during a median follow-up of 13.7 y. Comparing the highest to the lowest quartile, high intake of dodecanoic acid/lauric acid (C12:0) was associated with reduced risk of colorectal cancer among White participants (HR: 0.52; 95% CI: 0.30, 0.91; P-trend = 0.05), but not in Black individuals (HR: 0.92; 95% CI, 0.68, 1.24; P-trend = 0.80) in multivariable-adjusted models. No associations were found between intakes of hexanoic acid/caproic acid (C6:0), octanoic acid/caprylic acid (C8:0), or decanoic acid/capric acid (C10:0) and risk of incident colorectal cancer overall or within racial subgroups.

CONCLUSIONS

In a predominantly low-income United States population, an increased dietary C12:0 intake was associated with a substantially reduced risk of colorectal cancer only among White individuals, but not in Black individuals.

End-to-end donor screening and manufacturing controls: complementary quality-based strategies to minimize patient risk for donor-derived microbiome therapeutics

Advances in microbiome therapeutics have been motivated by a deeper understanding of the role that the gastrointestinal microbiome plays in human health and disease. The FDA approval of two stool-derived live biotherapeutic products (LBPs), REBYOTA® 150 mL enema (fecal microbiota, live-jslm; formerly RBX2660) and VOWST® oral capsules (fecal microbiota spores, live-brpk; formerly SER-109), for the prevention of recurrent CDI in adults following antibiotic treatment for recurrent CDI provides promise and insights for the development of LBPs for other diseases associated with microbiome dysfunction. Donor-derived products carry risk of disease transmission that must be mitigated through a robust donor screening program and downstream manufacturing controls. Most published recommendations for donor screening practices are prescriptive and do not include a systematic, risk-based approach for donor stool-derived products. A general framework for an end-to-end donor screening program is needed using risk management strategies for donor-derived microbiome therapeutic using a matrixed approach, combining the elements of donor screening with manufacturing controls that are designed to minimize risk to patients. A donor screening paradigm that incorporates medical history, physical examination, laboratory testing, and donor sample inspection are only the first steps in reducing risk of transmission of infectious agents. Manufacturing controls are the cornerstone of risk mitigation when screening unwittingly fails. Failure Mode and Effects Analysis (FMEA) can be used as a tool to assess for residual risk that requires further donor or manufacturing controls. Together, a well-reasoned donor program and manufacturing controls are complementary strategies that must be revisited and reexamined frequently with constant vigilance to mitigate risk to patients. In the spirit of full disclosure and informed consent, physicians should discuss any limitations in the donor screening and manufacturing processes with their patients prior to treatment with microbiome-based therapeutics.

Microbiome and its implications in oncogenesis: a Mendelian randomization perspective

The human microbiome, an intricate ecological network, has garnered significant attention due to its potential implications in oncogenesis. This paper delves into the multifaceted relationships between the microbiome, its metabolites, and cancer development, emphasizing the human intestinal tract as the primary microbial habitat. Highlighting the potential causative associations between microbial disturbances and cancer progression, we underscore the role of specific bacterial strains in various cancers, such as stomach and colorectal cancer. Traditional causality assessment methods, like randomized controlled trials (RCTs), have limitations. Therefore, we advocate using Mendelian Randomization (MR) as a powerful alternative to study causal relationships, leveraging genetic variants as instrumental variables. With the proliferation of genome-wide association studies, MR harnesses genetic variations to infer causality, which is especially beneficial when addressing confounders like diet and lifestyle that can skew microbial research. We systematically review MR's application in understanding the microbiome-cancer nexus, emphasizing its strengths and challenges. While MR offers a unique perspective on causality, it faces hurdles like horizontal pleiotropy and weak instrumental variable bias. Integrating MR with multi-omics data, encompassing genomics, transcriptomics, proteomics, and metabolomics, holds promise for future research, potentially heralding groundbreaking discoveries in microbiology and genetics. This comprehensive review underscores the critical role of the human microbiome in oncogenesis and champions MR as an indispensable tool for advancing our understanding in this domain.

Immunotherapy: Advancing glioblastoma treatment-A narrative review of scientific studies

BACKGROUND

Glioblastoma (GB) is an aggressive and deadly brain tumor with a poor prognosis despite the current standard of care, including surgery, radiation, and chemotherapy.

RECENT FINDINGS

In recent years, there has been increasing interest in the potential of immunotherapies, seen to be effective in treating other cancers, in the treatment of GB. This comprehensive review presents an in-depth analysis of the remarkable progress of immunotherapy in GB treatment, focusing on human clinical studies. It also analyzes the current findings, challenges, and limitations that underscore the transformative potential of immunotherapy in managing GB. Of particular significance, it delves into the intriguing interaction of the human microbiome with immunotherapy as a novel avenue for enhancing treatment outcomes of GB.

CONCLUSION

This study sheds light on the complex GB therapy landscape and the cutting-edge strategies that show promise for enhancing patient prognosis.

The Role of the Gut Microbiome in Cancer: A Review, With Special Focus on Colorectal Neoplasia and Clostridioides difficile

The gut microbiome has coevolved with humans to aid in physiologic functions and prevent disease. An increasing prevalence of gut dysbiosis in modern society exists and has strong linkages to multiple disease processes common in the developed world. Mechanisms for microbiome-human interactions that impact host homeostasis include bacterial metabolite/toxin production, biofilm formation with mucous layer infiltration, and host immune system modulation. Most of this crosstalk occurs at the epithelial layer of the gut, and as such the role of these interactions in the induction of colorectal cancer-a highly prevalent disease globally and one undergoing significant epidemiologic shifts-is under increasing scrutiny. Although multiple individual gut bacteria have been hypothesized as possible driver organisms in the oncogenic process, no bacterium has been definitively identified as a causal agent of colorectal cancer, suggesting that host lifestyle factors, microbiome community interactions, and the mucosal and/or systemic immune response may play a critical role in the process. Recent evidence has emerged implicating the ubiquitous human pathogen Clostridioides difficile as a possible promoter of colorectal cancer through chronic toxin-mediated cellular changes. Although much remains to be defined regarding the natural history of infections caused by this pathogen and its potential for oncogenesis, it provides a strong model for the role of both individual bacteria and of the gut microbial community as a whole in the development of colorectal cancer.

Drug resistance mechanism and reversal strategy in lung cancer immunotherapy

Among all malignant tumors, lung cancer has the highest mortality and morbidity rates. The non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) are the most common histological subtypes. Although there are a number of internationally recognized lung cancer therapy regimens, their therapeutic effects remain inadequate. The outlook for individuals with lung carcinoma has ameliorated partly thanks to the intensive study of the tumor microenvironment and immune checkpoint inhibitors. Numerous cancers have been effectively treated with immunotherapy, which has had positive therapeutic results. Global clinical trials have validated that PD-1/PD-L1 inhibitors are effective and safe for treating lung cancer either independently or in combination, and they are gradually being recommended as systemic treatment medications by numerous guidelines. However, the immunotherapy resistance restricts the immunotherapy efficacy due to the formation of tumor immunosuppressive microenvironment and tumor mutations, and immunotherapy is only effective for a small percentage of lung cancer patients. To summarize, while tumor immunotherapy is benefiting an increasing number of lung cancer patients, most of them still develop natural or acquired resistance during immunotherapy. Consequently, a crucial and urgent topic is understanding and tackling drug resistance triggered by immunotherapy in lung cancer treatment. This review will outline the presently recognized mechanisms of immunotherapy resistance and reversal strategies in lung cancer.

Assessment of bacterial and viral gut communities in healthy and tumoral colorectal tissue using RNA and DNA deep sequencing

BACKGROUND

Colorectal cancer (CRC) is known to present a distinct microbiome profile compared to healthy mucosa. Non-targeted deep-sequencing strategies enable nowadays full microbiome characterization up to species level.

AIM

We aimed to analyze both bacterial and viral communities in CRC using these strategies.

MATERIALS & METHODS

We analyzed bacterial and viral communities using both DNA and RNA deep-sequencing (Novaseq) in colorectal tissue specimens from 10 CRC patients and 10 matched control patients. Following taxonomy classification using Kraken 2, different metrics for alpha and beta diversities as well as relative and differential abundance were calculated to compare tumoral and healthy samples.

RESULTS

No viral differences were identified between tissue types, but bacterial species Polynucleobacter necessarius had a highly increased presence for DNA in tumors (p = 0.001). RNA analyses showed that bacterial species Arabia massiliensis had a highly decreased transcription in tumors (p = 0.002) while Fusobacterium nucleatum transcription was highly increased in tumors (p = 0.002).

DISCUSSION

Sequencing of both DNA and RNA enables a wider perspective of micriobiome profiles. Lack of RNA transcription (Polynucleobacter necessarius) casts doubt on possible role of a microorganism in CRC. The association of F. nucleatum mainly with transcription, may provide further insights on its role in CRC.

CONCLUSION

Joint assessment of the metagenome (DNA) and the metatranscriptome (RNA) at the species level provided a huge coverage for both bacteria and virus and identifies differential specific bacterial species as tumor associated.

Cellular and Molecular Mechanisms of the Tumor Stroma in Colorectal Cancer: Insights into Disease Progression and Therapeutic Targets

Colorectal cancer (CRC) is a major health burden worldwide and is the third most common type of cancer. The early detection and diagnosis of CRC is critical to improve patient outcomes. This review explores the intricate interplay between the tumor microenvironment, stromal interactions, and the progression and metastasis of colorectal cancer. The review begins by assessing the gut microbiome's influence on CRC development, emphasizing its association with gut-associated lymphoid tissue (GALT). The role of the Wnt signaling pathway in CRC tumor stroma is scrutinized, elucidating its impact on disease progression. Tumor budding, its effect on tumor stroma, and the implications for patient prognosis are investigated. The review also identifies conserved oncogenic signatures (COS) within CRC stroma and explores their potential as therapeutic targets. Lastly, the seed and soil hypothesis is employed to contextualize metastasis, accentuating the significance of both tumor cells and the surrounding stroma in metastatic propensity. This review highlights the intricate interdependence between CRC cells and their microenvironment, providing valuable insights into prospective therapeutic approaches targeting tumor-stroma interactions.

Waldeyer ring microbiome in relation to chemoradiation-induced oral mucositis in patients with nasopharyngeal carcinoma

BACKGROUND

Waldeyer lymphatic ring surrounds the nasopharynx and oropharynx, and no study to date has correlated its microbiome with the severity of oral mucositis (OM) in patients with nasopharyngeal carcinoma (NPC) receiving chemoradiotherapy.

METHODS

We performed 16S rRNA sequencing to characterize bacterial microbiome in tumor-affected nasopharynx and the surrounding normal oropharynx. We plotted the abundance and diversity of bacterial taxa and their phylogenetic distance and networks to visualize and compare the differences in pretreatment overall bacterial communities between the nasopharynx and oropharynx in patients with NPC with varying degrees of chemoradiotherapy-induced OM and quality of life.

RESULTS

We found microbial signatures in nasopharynx around NPC were not only dissimilar to those in the surrounding oropharynx but were almost unique to each patient. The genetic distance metrics further showed that different tumor microbiota distributions in the nasopharynx among patients with NPC were well-correlated with OM severity and quality of life during chemoradiotherapy.

CONCLUSIONS

At Waldeyer ring, the tumor-associated microbiome risk profiles of the respiratory region of nasopharynx, but not commensal microbiota of the alimentary region of oropharynx, could be noninvasive biomarkers for OM susceptibility and might include drug targets for the prevention of chemoradiation-induced OM in patients with Waldeyer ring-derived NPC.

Interactions between host and intestinal crypt-resided biofilms are controlled by epithelial fucosylation

As highly organized consortia of bacteria, biofilms have long been implicated in aggravating inflammation. However, our understanding regarding in vivo host-biofilm interactions in the complex tissue environments remains limited. Here, we show a unique pattern of crypt occupation by mucus-associated biofilms during the early stage of colitis, which is genetically dependent on bacterial biofilm-forming capacity and restricted by host epithelial α1,2-fucosylation. α1,2-Fucosylation deficiency leads to markedly augmented crypt occupation by biofilms originated from pathogenic Salmonella Typhimurium or indigenous Escherichia coli, resulting in exacerbated intestinal inflammation. Mechanistically, α1,2-fucosylation-mediated restriction of biofilms relies on interactions between bacteria and liberated fucose from biofilm-occupied mucus. Fucose represses biofilm formation and biofilm-related genes in vitro and in vivo. Finally, fucose administration ameliorates experimental colitis, suggesting therapeutic potential of fucose for biofilm-related disorders. This work illustrates host-biofilm interactions during gut inflammation and identifies fucosylation as a physiological strategy for restraining biofilm formation.

Role of the gut microbiota in anticancer therapy: from molecular mechanisms to clinical applications

In the past period, due to the rapid development of next-generation sequencing technology, accumulating evidence has clarified the complex role of the human microbiota in the development of cancer and the therapeutic response. More importantly, available evidence seems to indicate that modulating the composition of the gut microbiota to improve the efficacy of anti-cancer drugs may be feasible. However, intricate complexities exist, and a deep and comprehensive understanding of how the human microbiota interacts with cancer is critical to realize its full potential in cancer treatment. The purpose of this review is to summarize the initial clues on molecular mechanisms regarding the mutual effects between the gut microbiota and cancer development, and to highlight the relationship between gut microbes and the efficacy of immunotherapy, chemotherapy, radiation therapy and cancer surgery, which may provide insights into the formulation of individualized therapeutic strategies for cancer management. In addition, the current and emerging microbial interventions for cancer therapy as well as their clinical applications are summarized. Although many challenges remain for now, the great importance and full potential of the gut microbiota cannot be overstated for the development of individualized anti-cancer strategies, and it is necessary to explore a holistic approach that incorporates microbial modulation therapy in cancer.

Awareness of intratumoral bacteria and their potential application in cancer treatment

Hitherto, the recognition of the microbiota role in tumorigenesis and clinical studies mostly focused on the intestinal flora. In contrast to the gut microbiome, microorganisms resident in tumor tissue are in close contact with cancer cells and therefore have the potential to have similar or even different functional patterns to the gut flora. Some investigations have shown intratumoral bacteria, which might come from commensal microbiota in mucosal areas including the gastrointestinal tract and oral cavity, or from nearby normal tissues. The existence, origin, and interactions of intratumoral bacteria with the tumor microenvironment all contribute to intratumoral microorganism heterogeneity. Intratumoral bacteria have a significant role in tumor formation. They can contribute to cancer at the genetic level by secreting poisons that directly damage DNA and also intimately related to immune system response at the systemic level. Intratumoral bacteria have an impact on chemotherapy and immunotherapy in cancer. Importantly, various properties of bacteria such as targeting and ease of modification make them powerful candidates for precision therapy, and combining microbial therapies with other therapies is expected to improve the effectiveness of cancer treatment. In this review, we mainly described the heterogeneity and potential sources of intratumoral bacteria, overviewed the important mechanisms by which they were involved in tumor progression, and summarized their potential value in oncology therapy. At last, we highlight the problems of research in this field, and look forward to a new wave of studies using the various applications of intratumoral microorganisms in cancer therapy.

Chemoresistance in pancreatic ductal adenocarcinoma: Overcoming resistance to therapy

Pancreatic ductal adenocarcinoma (PDAC), a prominent cause of cancer deaths worldwide, is a highly aggressive cancer most frequently detected at an advanced stage that limits treatment options to systemic chemotherapy, which has provided only marginal positive clinical outcomes. More than 90% of patients with PDAC die within a year of being diagnosed. PDAC is increasing at a rate of 0.5-1.0% per year, and it is expected to be the second leading cause of cancer-related mortality by 2030. The resistance of tumor cells to chemotherapeutic drugs, which can be innate or acquired, is the primary factor contributing to the ineffectiveness of cancer treatments. Although many PDAC patients initially responds to standard of care (SOC) drugs they soon develop resistance caused partly by the substantial cellular heterogeneity seen in PDAC tissue and the tumor microenvironment (TME), which are considered key factors contributing to resistance to therapy. A deeper understanding of molecular mechanisms involved in PDAC progression and metastasis development, and the interplay of the TME in all these processes is essential to better comprehend the etiology and pathobiology of chemoresistance observed in PDAC. Recent research has recognized new therapeutic targets ushering in the development of innovative combinatorial therapies as well as enhancing our comprehension of several different cell death pathways. These approaches facilitate the lowering of the therapeutic threshold; however, the possibility of subsequent resistance development still remains a key issue and concern. Discoveries, that can target PDAC resistance, either alone or in combination, have the potential to serve as the foundation for future treatments that are effective without posing undue health risks. In this chapter, we discuss potential causes of PDAC chemoresistance and approaches for combating chemoresistance by targeting different pathways and different cellular functions associated with and mediating resistance.

Keystone pathobionts associated with colorectal cancer promote oncogenic reprograming

Fusobacterium nucleatum (Fn) and enterotoxigenic Bacteroides fragilis (ETBF) are two pathobionts consistently enriched in the gut microbiomes of patients with colorectal cancer (CRC) compared to healthy counterparts and frequently observed for their direct association within tumors. Although several molecular mechanisms have been identified that directly link these organisms to features of CRC in specific cell types, their specific effects on the epithelium and local immune compartment are not well-understood. To fill this gap, we leveraged single-cell RNA sequencing (scRNA-seq) on wildtype mice and mouse model of CRC. We find that Fn and ETBF exacerbate cancer-like transcriptional phenotypes in transit-amplifying and mature enterocytes in a mouse model of CRC. We also observed increased T cells in the pathobiont-exposed mice, but these pathobiont-specific differences observed in wildtype mice were abrogated in the mouse model of CRC. Although there are similarities in the responses provoked by each organism, we find pathobiont-specific effects in Myc-signaling and fatty acid metabolism. These findings support a role for Fn and ETBF in potentiating tumorigenesis via the induction of a cancer stem cell-like transit-amplifying and enterocyte population and the disruption of CTL cytotoxic function.

The Interaction between Intratumoral Microbiome and Immunity Is Related to the Prognosis of Ovarian Cancer

Microbiota can influence the occurrence, development, and therapeutic response of a wide variety of cancer types by modulating immune responses to tumors. Recent studies have demonstrated the existence of intratumor bacteria inside ovarian cancer (OV). However, whether intratumor microbes are associated with tumor microenvironment (TME) and prognosis of OV still remains unknown. The RNA-sequencing data and clinical and survival data of 373 patients with OV in The Cancer Genome Atlas (TCGA) were collected and downloaded. According to the knowledge-based functional gene expression signatures (Fges), OV was classified into two subtypes, termed immune-enriched and immune-deficient subtypes. The immune-enriched subtype, which had higher immune infiltration enriched with CD8+ T cells and the M1 type of macrophages (M1) and higher tumor mutational burden, exhibited a better prognosis. Based on the Kraken2 pipeline, the microbiome profiles were explored and found to be significantly different between the two subtypes. A prediction model consisting of 32 microbial signatures was constructed using the Cox proportional-hazard model and showed great prognostic value for OV patients. The prognostic microbial signatures were strongly associated with the hosts' immune factors. Especially, M1 was strongly associated with five species (Achromobacter deleyi and Microcella alkaliphila, Devosia sp. strain LEGU1, Ancylobacter pratisalsi, and Acinetobacter seifertii). Cell experiments demonstrated that Acinetobacter seifertii can inhibit macrophage migration. Our study demonstrated that OV could be classified into immune-enriched and immune-deficient subtypes and that the intratumoral microbiota profiles were different between the two subtypes. Furthermore, the intratumoral microbiome was closely associated with the tumor immune microenvironment and OV prognosis. IMPORTANCE Recent studies have demonstrated the existence of intratumoral microorganisms. However, the role of intratumoral microbes in the development of ovarian cancer and their interaction with the tumor microenvironment are largely unknown. Our study demonstrated that OV could be classified into immune-enriched and -deficient subtypes and that the immune enrichment subtype had a better prognosis. Microbiome analysis showed that intratumor microbiota profiles were different between the two subtypes. Furthermore, the intratumor microbiome was an independent predictor of OV prognosis that could interact with immune gene expression. Especially, M1 was closely associated with intratumoral microbes, and Acinetobacter seifertii could inhibit macrophage migration. Together, the findings of our study highlight the important roles of intratumoral microbes in the TME and prognosis of OV, paving the way for further investigation into its underlying mechanisms.

Causal relationship between gut microbiota and cancers: a two-sample Mendelian randomisation study

BACKGROUND

Evidence from observational studies and clinical trials suggests that the gut microbiota is associated with cancer. However, the causal association between gut microbiota and cancer remains to be determined.

METHODS

We first identified two sets of gut microbiota based on phylum, class, order, family, and genus level information, and cancer data were obtained from the IEU Open GWAS project. We then performed two-sample Mendelian randomisation (MR) to determine whether the gut microbiota is causally associated with eight cancer types. Furthermore, we performed a bi-directional MR analysis to examine the direction of the causal relations.

RESULTS

We identified 11 causal relationships between genetic liability in the gut microbiome and cancer, including those involving the genus Bifidobacterium. We found 17 strong associations between genetic liability in the gut microbiome and cancer. Moreover, we found 24 associations between genetic liability in the gut microbiome and cancer using multiple datasets.

CONCLUSIONS

Our MR analysis revealed that the gut microbiota was causally associated with cancers and may be useful in providing new insights for further mechanistic and clinical studies of microbiota-mediated cancer.

The Gut Microbiome and Metastatic Renal Cell Carcinoma

The introduction of targeted therapy (TT) and immuno-oncology (IO) agents have revolutionized the treatment of metastatic renal cell carcinoma (mRCC). However, despite the significant improvements in survival and clinical response yielded by these agents, a significant percentage of patients still experience progressive disease. Evidence now suggests that microorganisms living in the gut (i.e., the gut microbiome) could be used as a biomarker for response and may also have utility in increasing response to these treatments. In this review, we present an overview of the role of the gut microbiome in cancer and its potential implications in the treatment of mRCC.